1. Field of the Invention
The present invention relates to a method and system for inspecting a specimen using at least one probe.
2. Description of Related Art
Known specimen inspection systems for measuring the physical properties of a specimen in a scanning electron microscope (SEM) include an inspection system using an electron beam-induced current (EBIC) method and an inspection system using an electron beam LSI tester or cathodoluminescence. Of these systems, inspection systems using cathodoluminescence measure physical properties of specimens by a technique utilizing optical physical properties. On the other hand, in inspection systems using EBIC, a lead wire or interconnect line connected with a probe in contact with a wide-area electrode (usually known as a pad) or an interconnect line bonded to the pad is brought to the outside of the SEM specimen chamber, and the EBIC is measured outside the SEM.
One conventional system of this kind has a control means for irradiating a specimen with a focused electron beam and controlling the beam position on the specimen, a secondary electron detector, plural probes each having a sharp tip, a voltage source for applying a voltage between the probes, an ammeter for measuring the electrical current flowing between the probes, and a means for storing the value of the current flowing between the probes in a corresponding manner to the beam position on the specimen (see, for example, Japanese Patent Laid-Open No. 2001-185593 (pages 4 and 5; FIG. 1)).
Another conventional system of this kind consists basically of an SEM. Two or more metallic microprobes are mounted in the SEM. The probes are operated at high accuracy to precisely detect the electrical characteristics of microscopic areas of ceramics (see, for example, Japanese Patent Laid-Open No. H10-214584 (pages 3 and 4; FIG. 1)).
A further available method is used to inspect for defects in a specimen using an electron microscope or FIB (focused ion beam) system. In this method, an electrical potential produced on the specimen when it is scanned with an electron beam or ion beam is observed as a contrast difference. This potential difference imaging method visualizes abnormal potentials caused by charge-up as variations in brightness of secondary electrons when a specimen surface is irradiated with an electron beam or ion beam.
In the prior art potential difference imaging method, the difference in secondary electron emission efficiency between positively and negatively charged portions of a specimen is recognized as an image and so it has been impossible to detect minute variations in voltage.